We've moved this discussion to the PC Technical Support board as it seems like a more fitting place for your question.

For crashing in Cyrodiil, our first suggestion is to run a repair on the client just to make sure that everything is in order and without corruption. To do this, close the game and head to the launcher. Just above the news section, there is a button that says "Game Options." Click on this and select Repair from the drop-down menu.

If that doesn't assist with the crashing, our next suggestion is to use the new sliders implemented in 1.4.3 to lower the particle settings within the game. These sliders are in the Video section of the settings menu, and are called Maximum Particle Systems and Particle Suppression Distance. Lowering those sliders will increase your stability in Cyrodiil and other areas of the game.

If these suggestions don't help, please let us know and we'll be happy to continue assisting you.